Dust

Dust is a general name for minute solid particles with diameters less than 20 thou (500 micrometers). Particles in the atmosphere arise from various sources such as soil dust lifted up by wind, volcanic eruptions, and pollution. Dust in homes, offices, and other human environments consist primarily of human skin cells, but also contain small amounts of plant pollen, human and animal hairs, textile fibers, paper fibers, minerals from outdoor soil, and many other materials which may be found in the local environment.